Oncology Venture announced that patient enrollment has begun in a Phase 2 study evaluating irofulven as a possible treatment for metastatic castration-resistant prostate cancer (mCRPC).

Specifically, the trial (NCT03643107) is for patients who failed to respond to one or two prior androgen receptor-targeted therapies – including Zytiga (abiraterone acetate) and Xtandi (enzalutamide) – and to Taxotere (docetaxel) for their disease.

“The initiation of this Phase 2 study in prostate cancer patients is an important milestone in the development of Irofulven. This has been long under way but is as relevant as ever,” Peter Buhl Jensen, MD, CEO of Oncology Venture, said in a press release.

Irofulven is a man-made product that derives from a natural fungus toxin. It works by causing chemical changes in DNA that cancer cells are unable to repair – because they often have deficiencies in their DNA repair machinery – stopping them from dividing.

According to Venture, irofulven works similarly to PARP inhibitors now in clinical use, which also exploit the deficiencies in the DNA repair mechanism of cancer cells.

To date, irofulven has been tested in more than 19 clinical trials, including a Phase 3 study (NCT00033735) in patients with pancreatic cancer. Its therapeutic activity has been demonstrated against prostate, ovarian tumors, and liver cancers.

However, trials in prostate cancer have shown only a modest response rate (10%) in patients who had failed prior Taxotere.

It will enroll between 13 and 27 men with metastatic castration-resistant prostate cancer, who will receive irofulven into a vein on days one and eight of every three-week cycle. They will also be given oral prednisolone once daily.

The trial’s primary objective is to determine the proportion of patients achieving at least stable disease, but researchers will also measure the duration of responses, how long patients remain without signs of cancer progression on imaging scans, and survival. Blood levels of prostate specific antigen (PSA) will also be assessed as a biomarker of prostate cancer.

Taking place at one site in Copenhagen, the trial is currently recruiting; information is available here.

“Despite of the success of the drug class called PARP inhibitors and other new developments the reality is that unfortunately, most prostate cancer patients with metastatic disease will experience progression of their disease and we see a high potential for these patients to benefit from irofulven,” Jensen said.